Seroprevalence of Leishmania spp. in dogs in northern Serbia

Leishmaniosis is a zoonotic disease caused by Leishmania spp. Serbia was an endemic region for this disease until the second half of the 20th century. Nowadays, canine leishmaniosis appears to be a re-emerging vector-borne disease in Serbia. Its spread is enabled by the presence of Phlebotomus spp. sandflies in this region. The objective of this study was to establish the seroprevalence of Leishmania spp. in dogs being kept in shelters in Serbia and compare those that apply and those that do not apply prophylactic measures against arthropod vectors. This cross-sectional study involved 336 dogs in two regions in Northern Serbia during 2019-2020. A commercial enzyme-linked immunosorbent assay test was used to establish the prevalence of seropositive dogs. In the shelters that applied prophylactic measures against arthropod vectors, dogs were seronegative (n=52), while in those without these measures, 2.1% (6/284) were seropositive against Leishmania spp. In conclusion, the presence of dogs seropositive against Leishmania spp. in shelters that did not apply prophylactic measures may indicate that the local population of sandflies is a source of Leishmania spp. parasites.

In vitro protease inhibition and cytotoxicity of Aspergillus fumigatus biomolecules secreted under long-term aerated conditions

The fatality rate of invasive aspergillosis (IA) is still very high, especially in prolonged and untreated pulmonary cases. Aspergillus fumigatus is the main causative agent of IA and investigation of its metabolites could provide valuable insight into virulence factor(s) associated with this organism. We evaluated the A. fumigatus culture filtrate (CF) products generated during short- and long-term aerated and non-aerated conditions and tested for (i) inhibition of cysteine or serine proteases and (ii) cytotoxicity. In addition, the mathematical model was determined using response surface methodology (RSM) to estimate the influence of different fermentation conditions on A. fumigatus CF characteristics, predict enzyme inhibition and make possible correlations with in vivo conditions. Biosynthesis of A. fumigatus low molecular weight proteinaceous products (from 6.4 to 15.4 kDa) was observed after 6 days of growth under aerated and alkaline conditions. Also, only these CFs showed significant reduction in cell lines survival (Caco-2 and WISH 35.6% and 54.6%, respectively). Obtained results provide solid starting point for further studies that would include: (i) detailed chemical characterization of A. fumigatus CF, (ii) activity relationships and in vivo correlation with pathogenicity of prolonged pulmonary IA and (iii) possible use of biomolecules as diagnostic or therapeutic markers.